Attention has been focused on photoacoustic tomography (hereinafter will be referred to as “PAT”) as a method of specifically imaging neovascularization which occurs due to cancer. PAT is a method including illuminating an object with illuminating light (near infrared rays) and receiving a photoacoustic wave generated from the inside of the object by means of an ultrasound probe, thereby imaging the photoacoustic wave.
Non Patent Literature 1 describes a handheld type photoacoustic apparatus. This apparatus has a bundle fiber, which is fixed to a handheld type probe, for irradiation with light from a light source. Non Patent Literature 1, however, is silent on a contact between an illuminating light emitting surface and an object. Therefore, the illuminating light is emitted not only to the object but also into other space and, hence, there is room to improve the safety against the illuminating light.
This problem can be addressed by using the technique described in Patent Literature 1. FIGS. 7A and 7B illustrate a system configuration shown in Patent Literature 1. In FIG. 7, an energy emitting surface 101 is a surface for contact with skin from which energy, such as light, is emitted. A support structure 102 fixes the energy emitting surface 101 and is housed in a housing 104 with contact sensors 103 intervening therebetween. The contact sensors 103 are each configured to detect a contact between the energy emitting surface 101 and non-illustrated skin and are disposed to circumscribe the energy emitting surface 101. Energy emission is stopped unless the contact between the contact sensors 103 and the skin is detected. By so doing, energy irradiation is conducted only when the energy emitting surface 101 is completely in intimate contact with the skin, which leads to improved safety against energy irradiation.